问题 解答题

用简便方法计算:

1.29+3.7+0.71+6.3        528×78+472×78        46.5×99+46.5

125×89×8               12.37-5.32-4.68        12.5×(0.8+8)

答案

①1.29+3.7+0.71+6.3,

=(1.29+0.71)+(3.7+6.3),

=2+10,

=12;

②528×78+472×78,

=(528+472)×78,

=1000×78,

=78000;

③46.5×99+46.5,

=(99+1)×46.5,

=100×46.5,

=4650;

④125×89×8,

=125×8×89,

=1000×89,

=89000;

⑤12.37-5.32-4.68,

=12.37-(5.32+4.68),

=12.37-10,

=2.37;

⑥12.5×(0.8+8),

=12.5×0.8+12.5×8,

=10+100,

=110.

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